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What Is the Best Age to Join the Military? | Young vs. Older

After high school, many young people turn their attention to the military. The military isn’t only an opportunity to learn skills and serve your country but also offers numerous benefits for those who serve. However, you may want to think about the best age to join the military. 

The best age to join the military is 21-25 years old. While you can officially enlist when you’re 18 (or 17 if you have permission from your parents), waiting a few years will give you the maturity you need to thrive in the military. However, joining the military late offers some challenges. 

If you’re considering an exciting career in the military, you might wonder if it’s best to join straight for school or whether to give yourself a few years before you enlist. Read on to find out whether it’s best to join the military when you’re young or older.

At What Age Should You Join the Military?

The age you should join the military is in your early to mid-twenties, as you’ll have the self-knowledge to navigate military training and also have more life experience. However, each individual is unique and should decide based on their individual circumstances. 

This section considers the best age to join the military, first considering the legal age limits and data. An excellent way to investigate the best age to enlist is to look at the average age of active recruits in the US. 

The Average Age of Enlisted Military

United States Army rangers during a military operation

A study conducted by Stastica in 2020 found that the average age of active military professionals and members is 25 years and under. Only a third of the enlisted military were 26 to 30 years old.

In addition, another study found that 92% of recruits had a college degree, showing that they joined the military after at least three years of college study. 

Military Age Limits

The US military is made of different groups with different age requirements. For instance, if you want to enlist in the Army for active duty, you should be between 17 to 35. Meanwhile, if you want to join the Marine Corps, you should be between 17 and 28. 

In addition, the age limits change depending on the kind of service you want to do. There are several types of service within each group

  • Active service. An individual in active service is in the military full-time and typically lives and trains on a military base. They may be immediately deployed to fight or protect in times of conflict.
  • Reserve service. Individuals in the reserve service aren’t part of the active military and don’t live at a military base or carry out day-to-day military activities. However, they can be called into active duty when needed during wars and emergencies.
  • The National Guard. The National Guard is part of the Army and the Air Force. Each state typically controls the national guard, which can help during local emergencies like floods and fires as well as war. 

In case you’re unsure of which division of the military you wish to join, the following section explores the age limit to join each group of the military. 


The Army consists of trained land forces that include personnel trained in arms formations and tactics. Five significant traits characterize army professionals; Military Expertise, Stewardship, Trust, Honorable Service, and Esprit de Corps (morale).

Here are the age limits for army professionals: 

  • Active Duty: 17-35 years 
  • Reserve: 17-35 years
  • Guard: 17-35 years 

Marine Corps 

The Marine Corps can be deployed quickly and respond to various threats and emergencies. They’re essential personnel on US Navy ships; they protect the Navy base, gather intelligence, and conduct surveillance. 

Here are the age restrictions for the Marine Corps: 

  • Active Duty: 17-28 years
  • Reserve: 17-28 years
  • Guard: There’s no national guard for the Marine Corps. 


The Navy monitors and fights for the freedom of the sea, with each country’s Navy focused on protecting the sea that falls within their territory. They operate ships, submarines, aircraft carriers, and other vehicles to protect the seas. 

Here’s the age eligibility of Navy personnel: 

  • Active Duty: 17-39 years
  • Reserve: 17-39 years
  • Guard: The Navy doesn’t have a national guard. 

Air Force

Individuals in the US Air Force focus on protecting the US territory in the air and conducting various air missions. They also support land and sea forces. The Air Force has approximately 35 different subgroups that manage different areas of operation. 

Here’s the age range you should be to be eligible for the Air Force: 

  • Active Duty: 17-39 years 
  • Reserve: 17-38 years
  • Guard: 17-39 years

Space Force 

The US Space Force focuses on training space forces and protecting US interests and territories within space. At present, the US Space Force doesn’t present clear guidelines on the age limits within each group. However, you can’t join the Space Force if you’re above 35. 

For additional information, they recommend that you call their recruitment line at 1-800-423-8723 to assess your eligibility. The Space Force also recruits civilian professionals, so even if you’re too old to engage in active service, you still may be able to work for the Space Force in some capacity.

Coast Guard 

The US Coast Guard protects US water territories, including ports and shorelines. It focuses on being the first responder in the face of threats. It also focuses on safety and marine protection, and defense operations. 

The US Coast Guard has similar age limits to other parts of the military: 

  • Active Duty: 17-32 years
  • Reserve Duty: 17- 40 years
  • Guard: The Coast Guard doesn’t have a national guard. 

Is 21 a Good Age to Join the Military?

Very Young Military Recruit With American Flag in the Background

Twenty-one is a good age to join the military. You have the physical capacity to cope with the rigorous training and the maturity to maintain the disciple and focus you need. You’ll also get enough time within service to advance professionally. 

Here’s a breakdown of why joining the military at 21 is a good idea: 

  • Physical capabilities. At 21, you have stronger physiological capacities and may be better able to keep up with the training requirements than older people. 
  • Maturity. While you may want to join the military at 18, it’s best to wait for a few years before you join up. Young recruits say that when you’re just out of high school, you may not know what you want from life.
  • Time to advance professionally. If you’re joining at 21, you can ensure you have a long career of military service before you. This early recruitment will allow you the time and experience you need to climb up the ranks within the military. 

However, some may argue that at 21, you won’t have the maturity or experience of an older individual. In addition, you may not have the chance to meet a partner, have children and achieve some other significant milestones. 

Is 25 a Good Age to Join the Military?

Twenty-five is still a good age to join the military. You have the maturity and physical capability to navigate the military’s requirements. However, you may be older than other recruits and may have had to leave a family or loved ones behind. 

Here are some of the benefits of joining the military at 25

  • Maturity. You probably have experience working or studying at 25, which will give you maturity and experience that impact the way you train and make decisions. 
  • Qualifications. At 25, you have had the chance to earn a college degree and get a few years of professional experience. Depending on your degree, you may also be able to climb the military ranks faster. 

Is It Weird to Join the Military at 25?

It’s not weird to join the military at 25, although you might face some challenges. You may have a partner or have started a family, making military life more difficult. You’ll also be older than many of the recruits.

Here are some of the challenges you may face when joining the military at 25: 

  • Family and friends. At 25, you’ve likely put some roots down as a civilian. You may even have met a partner or started a family. 
  • Age difference. You may find that many of your fellow recruits are younger than you. This division may affect the dynamics between you and your fellow training mates.

Is 30 a Good Age to Join the Military?

Group of both younger and older military soldiers standing with rifles at boot camp

Thirty isn’t a good age to join the military, although some branches accommodate older recruits. It would be best to consider your physical capacity and ability to adapt to new routines as well as your partner and children (if you have them). 

Before joining the military at 30, you should think about: 

Your Physical Capacity

A study by Abt et al. (2016) found that soldiers between 30-40 had a higher percentage of body fat and lowered aerobic capacity than their younger counterparts. Because your body structure changes as you get older, you may find it harder to keep up with the physical demand of the military, especially if you’re a recruit. You should carefully consider your physical capacity before joining the military. 

Your Family

If you’ve already established a family, joining the military will likely throw your family life into upheaval. You would most likely need to uproot your family or face separation from your loved ones if you join active service.  However, some military groups and schemes allow your family to join you when you’re training. 

While 30 isn’t the ideal age to join the military, there are some benefits to joining: 

  • Benefits. Military service personnel benefits include housing, education, and healthcare. Some effective programs can offer support to families or provide student loans for further study.  
  • Character building. If you’re looking to improve your disciple and build on skills, the military is a great place to do this. It’ll offer you a structure and routine that no other place in the civilian world will. 
  • Retirement plans. Depending on the time and station from which you retire, you may be able to reap retirement plans and pensions as ex-military service personnel. 

While most groups within the military allow you to enlist at 30, you should remember that you can’t join the Marine Corps at 30. 

Can a 45-Year-Old Join the Military?

A 45-year-old cannot join the military as they’ve exceeded the maximum age limit to join active service in the military. The US Federal Law states that the maximum age to enlist in the military is 42 years. However, if you wish to serve your country, you can help the military as a civilian

Army civilians aren’t army members but instead serve the Army by providing services, food, maintaining transport lines, and performing other services integral to the functioning of the Army.

Can You Become a Navy SEAL at 30?

You cannot become a Navy SEAL at 30 as the specified age is between 17-28 years old. However, if you’re highly qualified, you can request a waiver to become a SEAL at 30. This waiver would only be in relatively rare circumstances, and generally, a 30-year-old won’t gain admission.  

Here are some of the qualification requirements you must fulfill to become a Navy SEAL. These are the minimum requirements, so to get a waiver to apply at 30, you’ll need to surpass these: 

  • Physical screening. One of the main requirements is to complete swimming tasks, push-ups, sit-ups, and pull-ups in a given time. 
  • Vision. Your vision must be correctable to 20/25.
  • Secret security clearance. You should have a secret security clearance. 
  • Psychological battery test. You should complete a series of psychological tests that gauge whether you have the mental fortitude to be a Navy SEAL.

Reasons To Join the Military When You Are Young

Joining the military young has its advantages. The military can give young recruits direction and discipline and prevent the potential pitfalls of leaving school without a planned course of action. 

Rod Powers, author and a veteran of 23 years in the Air Force, points out that 40% of recruits drop out before their full term of service due mainly to realizing that the military life didn’t suit them. Younger people are less inclined to know themselves and what they genuinely need, which puts them at a disadvantage when joining the military early.

Other benefits and disadvantages of joining the military when young include:


  • Recruits are at their physical peak in strength and body condition.
  • Younger recruits may pass through the ranks while younger.
  • Young recruits find discipline and direction in the military.
  • Your military benefits will pay for a college degree.
  • You can retire by the time you’re 40. 


  • You may not be mentally mature enough for the decision.
  • You may not have enough maturity to deal with the pressures of training.
  • You may change your mind about your future career.
  • Older recruits with college degrees are more likely to get promotions.

Reasons To Wait Until You Are Older

Marine Corps veterans such as Matt Young warn that military training from an early age may cause lasting effects on young men’s psyches. Often young recruits choose the military through a lack of other options and don’t fully understand the implications of their decision. 

Other veterans such as Tom Marquell caution younger recruits to make sure they’re 110% committed to a military path as the military isn’t the place ‘to find oneself.’ Older recruits tend to have more self-knowledge and experience to make this decision.

Joining the military when you are older has advantages and disadvantages.


  • With more maturity, one can make a more informed decision about one’s life career.
  • Mental maturity aids recruits in dealing with the pressures and stress of becoming a soldier.
  • Older recruits have the advantage of completing a degree before joining the military. 


  • You might find yourself older than most of the other recruits.
  • Your body may not be in peak physical condition.
  • You may have already established social ties, such as a partner and a family.  


Joining the military is a momentous, life-changing decision, and there are various factors you should consider before deciding whether you’re ready. One of the most critical factors is your age — it’s best to join the military when you’re 21-25 years old. However, you may still opt for the military at an earlier or later age, factoring in the potential challenges.

For more, check out How To Get Military Training Without Joining.